Structure determination and structure-activity relationship of DOP Arelated compounds

我们提出L-3，4-二羟基苯丙氨酸(DOPA)是多巴胺的前体，是中枢神经系统的神经递质。然而，其特异性受体(S)尚未确定。在本研究中，我们试图确定多巴酚A识别位点(S)的特异性配体，即多巴酚A受体(S)，并利用血压监测系统研究麻醉大鼠的构效关系。向孤束核内微量注射去甲肾上腺素的前体多巴或L-苏氨酸，可引起降压和心动过速反应。通过高效液相色谱分析，我们发现了DOPA或DOPS溶液的活性部分，而不是DOPA和DOPS本身的活性部分，可以引起降压和心动过缓反应。我们分别从含有DOPA和DOPS的溶液中获得了A113和S122组分，这两个组分都能有效地诱导麻醉大鼠的心血管反应。此外，这些反应可被L-多巴环状…拮抗多巴的竞争性拮抗剂多巴胆碱酯(DOPA ChE)，从而提示多巴和多巴溶液中的一些未知活性物质通过多巴的识别位点(S)诱导降压和心动过缓反应。我们正在努力进一步纯化、鉴定和确定这些物质的结构。第二个项目旨在鉴定和鉴定线虫中的DOPA受体候选基因C06H5.7。利用非洲爪哇卵母细胞表达系统，我们鉴定了一个候选的G蛋白偶联受体，该受体在ASH化学感觉神经元中表达，介导对DOPA C06H5.7的电流反应。在C06H5.7突变动物中，对未稀释的苯甲醛的回避反应减弱，但对正辛醇的回避反应不减弱。当C06H5.7在ASH神经元中外源表达时，挽救了对苯甲醛的反应性。此外，我们还在线虫体内发现了一种作用于该受体的新型驱避剂--水溶性物质。这些结果表明，C06H5.7不是DOPA的受体，而是第一个介导对挥发性和水溶性化学反应物的厌恶反应的化学感觉受体。较少

We have proposed that L-3,4-dihydroxyphenylalanine (DOPA), the precursor of dopamine, is a neurotransmitter in the central nervous system. However its specific receptor(s) have not been determined yet. In this proposal, we have tried to identify specific ligands for DOPA recognistion site(s), namely DOPAreceptor(s), and investigate structure-activity relationship by using blood-pressure monitoring system in anaesthetized rats. DOPA or L-threo-DOPS, a precursor of noradrenaline, when microinjected into the nucleus tractus solitarii (NTS), induces depressor and baradycardic responses. By using HPLC, we found an active fraction of DOPA or DOPS-containing solution other than that of DOPA and DOPS itself that induced depressor and bradycardic responses. We obtained A113 and S122 fractions from DOPA and DOPS-containing solutions, respectively, both of which were active in inducing the cardiovascular responses in anaesthetized rats. In addition, these responses were antagonized by L-DOPA cycl … More ohexylester (DOPA CHE), an competitive antagonist for DOPA, thereby suggesting that some unknown active substances in DOPA and DOPS solution induced depressor and bradycardic responses through the recognition site(s) for DOPA. We are now trying further purification, identification and structural determination of these substances.The second project aimed at identification and characterization of a DOPA receptor candidate gene, C06H5.7 in C elegans. Using Xenopus laevis oocyte expression system, we identified a candidate G-protein-coupled receptor, that mediates current response to DOPA C06H5.7 was expressed in ASH chemosensory neurons. In C06H5.7 mutant animals, the avoidance response to undiluted benzaldehyde, but not to 1-octanol, was attenuated. C06H5.7, when exogenously expressed in ASH neurons, rescued the responsiveness to benzaldehyde. Furthermore, we found some water-soluble substance as a novel repellent acting on this receptor in C elegans. These results indicate that C06H5.7 is not a receptor for DOPA but the first chemosensory receptor that mediates aversive response to volatile and water soluble chemorepellents. Less